1. Field of the Invention
The present invention relates to a display device for displaying information input thereto. It is particularly, but not exclusively, concerned with the recognition and display of handwritten characters and figures.
2. Summary of the Prior Art
It is known to provide a device for recognizing handwritten characters and figures, and inputting recognized characters to a computer system. For example, in U.S. Pat. No. 4,672,677 there is shown a character and figure processing apparatus in which characters are input via a suitable stylus to an input tablet, and that input tablet then transmits information concerning the character to a computer. That computer then recognizes the character, and the character may then be displayed on the computer screen. Thus, in U.S. Pat. No. 4,672,677, the input table replaces the computer keyboard. A similar input tablet is shown in Japanese patent application laid-open number 58-144287.
In the above two disclosures, the processor and display for recognizing the character, and the display screen for processing and displaying the character are the processor and the display of a standard computer. However, it is also known to combine the computer and display screen in a composite device. An example of this is shown in GB 2193827, in which an input screen and a display screen are bonded together and connected to a micro-computer. The input screen detects the physical contact of a stylus therewith, and generates information concerning the position of contact which is transmitted to the micro-computer. That micro-computer analyzes the positional information to recognize the character being written on the input screen, and the recognized character is then transmitted to the display screen. The device shown in GB 2193827 may also have an output interface for connecting the display device to an external computer. Other examples of the integration together of a character input pad and a display screen are shown in e.g. U.S. Pat. No. 468,804, DE 351353, U.S. Pat. No. 4,641,354, and U.S. Pat. No. 4,639,720.
However, when such a display device is connected to an external computer, there are limitations on the performance thereof. With the arrangement of GB 2193827, information input to the input screen thereof can be readily transmitted to the external computer. However, it is not readily possible to transmit screen information from the computer to the display device, to enable the screen device to be used as a screen of an external computer. If a standard interface was used, such as an RS232C interface, then transmission of screen information from the external computer to the display device will be slow. An RS232C interface serially transmits coding data using a predetermined protocol. This protocol requires a large amount of time for transmission, and therefore it is not readily possible to use the screen of the display device as the screen of the computer.
It should also be mentioned that it is known from Japanese patent application laid-open number 63-1187887 to provide a display system which combines video information from a computer and from a separate display device. However, in that system, there is simply switching between the two types of inputs to the screen of the device, and that screen is a simple one, with the computer having its own separate input.